Electric machines are utilized in a wide variety of applications. For example, hybrid/electric vehicles (HEVs) typically include an electric traction drive system that includes a multi-phase alternating current (AC) electric motor which is driven by a power converter with a direct current (DC) power source, such as a storage battery. Motor windings of the AC electric motor can be coupled to inverter sub-modules of a power inverter module (PIM). Each inverter sub-module includes a pair of switches that switch in a complementary manner to perform a rapid switching function to convert the DC power to AC power. This AC power drives the AC electric motor, which in turn drives a shaft of HEV's drivetrain.
For instance, some traditional HEVs implement two three-phase pulse width modulated (PWM) inverter modules and two three-phase AC machines (e.g., AC motors) each being driven by a corresponding one of the three-phase PWM inverter modules that it is coupled to.
In such multi-phase systems, voltage command signals are applied to a pulse width modulation (PWM) module. The PWM module applies PWM waveforms to the phase voltage command signals to control pulse width modulation of the phase voltage command signals and generate switching vector signals that are provided to the PWM inverter module.
However, in many systems, due to factors such as switching limitations, and voltage drops in bus bars, terminals, and cables, the voltages that are applied at the machine terminals will exhibit non-linearity with respect to commanded phase voltages. As a result, the wrong phase voltage will be applied to the machine, and therefore, phase current may not be properly regulated, which may in turn cause current/torque oscillations.
It would be desirable to provide a mechanism for reducing or eliminating such non-linearities in the commanded phase voltages so that correct voltages will be applied at terminals of a multi-phase machine to help maintain proper phase current regulation. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.